Generally, the widely-used peripheral input device of a computer system includes for example a mouse device, a keyboard, a trackball device, or the like. Via the keyboard, characters and symbols can be inputted into the computer system directly. As a consequence, most users and most manufacturers of input devices pay much attention to the development of keyboards.
FIG. 1 is a schematic top view illustrating the outer appearance of a conventional keyboard. As shown in FIG. 1, there are plural keys 10 on a surface of the conventional keyboard 1. These keys 10 are classified into several types, e.g. ordinary keys 101, numeric keys 102 and function keys 103. When one of these keys 10 is depressed by the user's finger, a corresponding signal is issued to the computer, and thus the computer executes a function corresponding to the depressed key. For example, when an ordinary key 101 is depressed, a corresponding English letter or symbol is inputted into the computer. When a numeric key 102 is depressed, a corresponding number is inputted into the computer. In addition, the function keys 103 (F1˜F12) can be programmed to provide various functions. For example, the conventional keyboard 1 is a keyboard for a notebook computer.
With the maturity of the computing technologies, the keyboard manufacturers make efforts in designing novel keyboards with special functions in order to meet diversified requirements of different users. For this reason, luminous keyboards are favored by users. The outer appearance of the conventional luminous keyboard is substantially similar to the outer appearance of the conventional keyboard 1. Since the luminous keyboard provides the function of illuminating the keys, the inner structure of the luminous keyboard is different from the inner structure of the keyboard without the illuminating function. Hereinafter, the inner structure of the luminous keyboard will be illustrated in more details. FIG. 2 is a schematic cross-sectional view illustrating a conventional luminous keyboard. As shown in FIG. 2, the conventional luminous keyboard 2 comprises plural keys 20, a membrane switch circuit member 21, a supporting plate 22 and a backlight module 23. Each key 20 comprises a keycap 201, a scissors-type connecting element 202 and an elastic element 203. In the key 20, the keycap 201 is exposed outside the conventional luminous keyboard 2, so that the keycap 201 can be depressed by the user. The scissors-type connecting element 202 is used for connecting the keycap 201 and the supporting plate 22. The elastic element 203 is penetrated through the scissors-type connecting element 202. In addition, both ends of the elastic element 203 are contacted with the keycap 201 and the membrane switch circuit member 21, respectively. The supporting plate 22 is located under the membrane switch circuit member 21. The keycap 201, the scissors-type connecting element 202, the elastic element 203 and the membrane switch circuit member 21 are supported on the supporting plate 22.
The membrane switch circuit member 21 comprises an upper wiring board 211, a separation layer 212, and a lower wiring board 213. The upper wiring board 211, the separation layer 212 and the lower wiring board 213 are all made of a light-transmissible material. The light-transmissible material is for example polycarbonate (PC) or polyethylene (PE). The upper wiring board 211 has plural upper contacts 2111. The separation layer 212 is located under the upper wiring board 211, and comprises plural perforations 2121 corresponding to the plural upper contacts 2111. The lower wiring board 213 is located under the separation layer 212, and comprises plural lower contacts 2131 corresponding to the plural upper contacts 2111. The plural lower contacts 2131 and the plural upper contacts 2111 are collectively defined as plural key switches 214.
The backlight module 23 comprises a light guide plate 230, a circuit board 231, plural light-emitting elements 232, a reflecting plate 233 and a light-sheltering plate 234. For clarification and brevity, only two light-emitting elements 232 are shown in the drawing. The light guide plate 230 is located under the supporting plate 22. The circuit board 231 is located under the membrane switch circuit member 21 and electrically connected with the light-emitting elements 232. The circuit board 231 provides electric power to the plural light-emitting elements 232. The plural light-emitting elements 232 are disposed on the circuit board 231. In addition, the plural light-emitting elements 232 are inserted into plural reflecting plate openings 2331 of the reflecting plate 233 and plural light guide plate openings 2301 of the light guide plate 230, respectively. By acquiring the electric power, the plural light-emitting elements 232 are driven to emit plural light beams B. Moreover, the plural light beams B are introduced into the light guide plate 230. After portions of the light beams B are exited from the light guide plate 230, the light beams B are reflected back into the light guide plate 320 by the reflecting plate 233. The light-sheltering plate 234 is located over the light guide plate 230 for sheltering the light beams B. For example, the plural light-emitting elements 232 are side-view light emitting diodes. After the light beams B are introduced into the light guide plate 230, the light beams B are subjected to total internal reflection within the light guide plate 230. Then, the light beams B are guided to the keycap 201 by the light guide plate 230.
From top to bottom, the keycap 201, the scissors-type connecting element 202, the elastic element 203, the membrane switch circuit member 21, the supporting plate 22, the light-sheltering plate 234, the light guide plate 230 and the reflecting plate 233 of the conventional luminous keyboard 2 are sequentially shown. For example, the conventional luminous keyboard 2 is a keyboard for a notebook computer (not shown).
In the conventional luminous keyboard 2, each keycap 201 has a light-outputting zone 2011. The light-outputting zone 2011 is located at a character region or a symbol region of the keycap 201. Moreover, the position of the light-outputting zone 2011 is aligned with the position of a corresponding light-guiding dot 2302 of the light guide plate 230. The light beams can be guided upwardly to the light-outputting zone 2011 by the corresponding light-guiding dot 2302. The light-sheltering plate 234 comprises plural light-sheltering plate openings 2341. The plural light-sheltering plate openings 2341 are aligned with the corresponding light-guiding dots 2302 and the corresponding light-outputting zones 2011. Consequently, the light beams B are transmitted through the light-sheltering plate openings 2341 of the light-sheltering plate 234. Similarly, the supporting plate 22 comprises plural supporting plate openings 221. The plural supporting plate openings 221 are aligned with the corresponding light-guiding dots 2302 and the corresponding light-outputting zones 2011. Consequently, the light beams B are transmitted through the supporting plate openings 221 of the supporting plate 22.
On the other hand, since the membrane switch circuit member 21 is made of the light-transmissible material, the plural light beams B can be transmitted through the membrane switch circuit member 21. Consequently, after the plural light beams B are guided by the light-guiding dots 2302, the plural light beams B are sequentially transmitted through the plural supporting plate openings 221 and the membrane switch circuit member 21 and directed to the plural light-outputting zones 2011, thereby illuminating the character region or the symbol region of the keycap 201. Under this circumstance, the illuminating function is achieved.
Please refer to FIG. 2 again. For sealing the light guide plate 230, the lateral edges 2332 of the reflecting plate 233 have to be attached on the light-sheltering plate 234. Consequently, the light beams B are not leaked from the lateral edges of the light guide plate 230. That is, the problem of causing light leakage will be eliminated. Since the lateral edge 2332 of the reflecting plate 233 is attached on the light-sheltering plate 234, the attaching structure between the lateral edges 2332 of the reflecting plate 233 and the light-sheltering plate 234 occupies a space, it is difficult to reduce the volume of the luminous keyboard.
Therefore, there is a need of providing a luminous keyboard with reduced volume and capable of solving the lateral light leakage problem.